I have an 8x MSI 5700XT Gaming X platform. I have done Memory Toimming in all of them modifying the BIOS, and I get 54Mhs in each of them with memory at 1750.
The problem is when I try to increase the OC speed of the memory, to obtain a greater number of MHS, my Rig crash in random times, sometimes a few hours, sometimes many hours, sometimes a matter of minutes ... there are times that one of the graphics cards is placed at 0Mhs and within a few seconds the PC crashes, Other times PhoenixMiner gives an error with a lot of hexadecimal figures and freezes, and every few hours I have to restart the PC and restart everything.
...
pay attention to the temperature of the memory, if it exceeds 100-105 degrees, then crashes are quite likely, especially if you are still trying to speed it up beyond 1750, the probability of failure increases with increasing heating